Draft a Technical Design Doc From a PRD
Converts a product PRD into a technical design doc skeleton covering architecture, data model, APIs, and risks. Built for TPMs partnering with engineers on early technical scoping.
When to use this prompt
Use this when you have an approved PRD and need a starting point for the technical design doc the engineering team will fill in. You will need the PRD and any technical context you have (existing system architecture, constraints). The prompt cannot generate real technical decisions, but it can produce a scaffolded document that the tech lead can refine, saving them the cold-start overhead. Best used when the TPM and tech lead are collaborating closely in the scoping phase, and when there is no existing design doc to copy from. Do not use this as a replacement for engineering design.
The Prompt
You are a technical product manager producing a design doc skeleton from an approved PRD. The skeleton should match the Google-style design doc template and give the engineering team a clear starting structure to fill in. PRD: {{prd_text}} Existing system context: {{system_context}} Known technical constraints: {{constraints}} Produce the skeleton with these exact sections: 1. CONTEXT â 3-4 sentences on why this work matters. Pull directly from the PRD problem statement. No new content. 2. GOALS â Bulleted list of technical outcomes the design must achieve. Convert product goals from the PRD into technical language. 3. NON-GOALS â Explicit list of what this design will NOT cover. Pull from the PRD out-of-scope section and add any technical scope limits you can infer. 4. PROPOSED DESIGN (placeholder) â Leave a stub with these subsections to fill in: High-level architecture, Data model, APIs, UI integration points, Migration strategy. For each subsection, write 1 sentence describing what the engineer should document. Do NOT invent architectural decisions. 5. ALTERNATIVES CONSIDERED (placeholder) â Stub with 2-3 named alternatives based on common patterns for this type of problem (e.g., "in-process vs. separate service," "SQL vs. NoSQL"). Mark each as TO BE EVALUATED. 6. RISKS AND OPEN QUESTIONS â List the technical questions raised by the PRD that the design must resolve. Pull any risks from the PRD and add inferred technical risks. 7. ROLLOUT AND OBSERVABILITY â Sketch how the feature should be deployed (feature flag, migration, etc.) and what observability is needed. Use the PRD rollout section as input. Keep it a skeleton. Do not invent technical details the PRD does not support. The value is structure, not content.
Example Output
CONTEXT Billing admins lose 20 minutes a day exporting invoices to Excel to sort by overdue status. This causes a 9-day average delay in collections. We are adding an overdue-first sort and visual indicators to the existing invoices dashboard. GOALS - Surface overdue invoices first in the default dashboard sort without affecting existing filters. - Compute overdue status server-side to avoid client clock drift. - Support custom overdue thresholds per account (some customers use 30 days, others 45). NON-GOALS - No automated reminder emails. - No SMS or push notifications. - No changes to invoice creation or editing flows. - No new data exports beyond existing CSV. PROPOSED DESIGN (placeholder) - High-level architecture: [EM to document. Consider impact on invoices service.] - Data model: [No new tables expected. Document how overdue is computed from existing fields.] - APIs: [List new or modified endpoints.] - UI integration: [Existing dashboard component. Document sort control changes.] - Migration: [None expected; compute-only change.] ALTERNATIVES CONSIDERED (placeholder) - Compute overdue server-side (favored) â TO BE EVALUATED. - Compute overdue client-side (rejected; timezone risk). - Materialized overdue table (TO BE EVALUATED if performance is a concern). RISKS AND OPEN QUESTIONS - Per-account threshold: does our current data model support it? (EM to confirm) - Timezone handling for overdue computation (EM and SRE review) - Impact on dashboard load time at scale (EM to benchmark) ROLLOUT AND OBSERVABILITY - Feature flag behind beta cohort. - Instrument overdue sort toggle and row click events. - Add SLO for dashboard load time after change.
Recommended Tools
Notion and Coda both render the design doc skeleton cleanly and support inline engineering comments during the fill-in phase. Google Docs (via Google Workspace) is the incumbent for design docs in most engineering cultures and supports suggestion-mode review. Pick whichever your engineering team already uses; the skeleton transfers across all three without loss of structure.
Frequently Asked Questions
When should I use this prompt?
Use it after a PRD is approved and before the tech lead starts writing the design doc from scratch. It saves 30-60 minutes of cold-start time by scaffolding the document structure, letting the engineer focus on the actual technical decisions. Do not use it on trivial features where a design doc would be overkill, or when the tech lead already has a strong opinion on structure. Also skip it when the engineering team prefers to write design docs in a non-standard format; the skeleton may clash with their conventions.
Should the PM make technical decisions in the design doc?
No. The prompt is explicitly a skeleton; the proposed design and alternatives sections are placeholders for engineers to fill in. The PM's job is to ensure the PRD context flows into the design doc cleanly and to flag the technical questions raised by product requirements, not to make architectural calls. If the PM starts making technical decisions in the design doc, tensions with engineering almost always follow. Respect the handoff line: PM writes the problem, engineers write the solution.